In a known safety switch mechanism that is adapted to be fitted to an enclosure having a door, gate or protective cover, the switch assembly is adapted to switch OFF an electrical power supply when the door, gate or protective cover is opened. The known safety switch mechanism comprises a safety switch assembly adapted to be fitted to the enclosure and an actuator adapted to be fitted to the door, gate or protective cover, and insertable into the safety switch assembly to turn ON the electrical power when the enclosure is closed by the door, gate or protective cover.
The safety switch assembly comprises within a housing at least a pair of contacts, one set stationary and the other movable and carried by an axially movable carrier. In one known device movement of the carrier is controlled by a rotary cam mechanism rotatably mounted in a cam housing which actuates a plunger for the carrier to transmit movement of the rotary cam mechanism to the contact carrier.
The part of the housing accommodating the contacts, hereinafter referred to as the contact housing, has to be sealed to inhibit the ingress of water and dirt and to that end a sealing element in the form of a bellows seal is used. It has an outer peripheral rim and an inner peripheral rim. The latter is fitted onto the plunger and the former is trapped between the cam housing and the contact housing on assembly thereof.
Fitting of the inner periphery of the bellows seal on to the plunger limits the shape and/or design of the plunger to one that will accept the inner periphery of the seal. Furthermore, repeated operation of the plunger can impair sealing efficiency of the seal with the plunger. Furthermore, fitting of the seal onto the plunger complicates the assembly procedure. It is an aim of the present invention to provide an improved construction.